This invention relates to devitalized acellular tissue regeneration compositions, methods of making, and methods of use.
Submucosal tissues of warm-blooded vertebrates are useful in tissue grafting materials. For example, submucosal tissue graft compositions derived from small intestine have been described in U.S. Pat. No. 4,902,508 (hereinafter the ""508 patent) and U.S. Pat. No. 4,956,178 (hereinafter the ""178 patent), and submucosal tissue graft compositions derived from urinary bladder have been described in U.S. Pat. No. 5,554,389 (hereinafter the ""389 patent). All of these compositions consist essentially of the same tissue layers and are prepared by the same method, the difference being that the starting material is small intestine on the one hand and urinary bladder on the other. The procedure detailed in the ""508 patent, incorporated by reference in the ""389 patent and the procedure detailed in the ""178 patent, includes mechanical abrading steps to remove the inner layers of the tissue, including at least the luminal portion of the tunica mucosa of the intestine or bladder, i.e., the lamina epithelialis mucosa (epithelium) and lamina propria, as detailed in the ""178 patent. Abrasion, peeling, or scraping the mucosa delaminates the epithelial cells and their associated basement membrane, and most of the lamina propria, at least to the level of a layer of organized dense connective tissue, the stratum compactum. Thus, the tissue graft material previously recognized as soft tissue replacement material is devoid of epithelial basement membrane and consists of the submucosa and stratum compactum.
The epithelial basement membrane is a thin sheet of extracellular material contiguous with the basilar aspect of epithelial cells. Sheets of aggregated epithelial cells of similar type form an epithelium. Epithelial cells and their associated epithelial basement membrane are positioned on the luminal portion of the tunica mucosa and constitute the internal surface of tubular and hollow organs and tissues of the body. Epithelial cells and their associated epithelial basement membrane are also positioned on the external surface of the body, i.e., skin. Examples of a typical epithelium having a basement membrane include, but are not limited to the following: the epithelium of the skin, intestine, urinary bladder, esophagus, stomach, cornea, and liver.
Epithelial cells are positioned on the luminal or superficial side of the epithelial basement membrane, opposite to connective tissues. Connective tissues, the submucosa, for example, are positioned on the abluminal or deep side of the basement membrane. Examples of connective tissues that are positioned on the abluminal side of the epithelial basement membrane are the submucosa of the intestine and urinary bladder, and the dermis and subcutaneous tissues of the skin.
The present invention provides devitalized tissue regenerative compositions comprising an epithelial basement membrane as part of a matrix or scaffold for tissue repair or regeneration. The inclusion of the epithelial basement membrane in devitalized mammalian tissue regenerative compositions results in improved in vivo endogenous cell propagation and tissue restoration as compared to submucosal matrices described above which do not include an epithelial basement membrane. For the purposes of this invention, devitalized means acellular or substantially acellular. For the purposes of this invention, epithelial basement membrane means at least a portion of the intact epithelial basement membrane.
According to the invention, a preferred devitalized matrix for mammalian tissue repair or regeneration comprises at least a portion of a mammalian epithelial basement membrane, preferably the entire epithelial basement membrane, and the tunica propria that is immediately subjacent to the basement membrane. Devitalized matrices of the invention restore or replace diseased, defective, or missing tissue when placed in contact with host tissue. In a preferred embodiment, the invention comprises a devitalized matrix that is custom-shaped to conform to the diseased or defective tissue. In a particular embodiment, the matrix comprises a sheet of matrix derived from the urinary bladder, the intestine, or any other mammalian epithelial tissue. In another embodiment, the matrix is injectable by means of being transformed into a fine particulate, emulsion, gel or extract. A matrix of the invention may act as a carrier for a pharmaceutical agent. A preferred application of the matrix of the invention is the repair or restoration of cardiac tissue. In particular, a matrix or composition of the invention is useful to restore or replace at least a portion of a cardiac valve, the interatrial septum, the interventricular septum, or the myocardium. For the purposes of this invention, matrix and composition are interchangeable terms.
In one embodiment, the invention features a devitalized composition comprising epithelial basement membrane and tunica propria immediately subjacent to the basement membrane. The epithelial basement membrane and tunica propria immediately subjacent to the basement membrane are delaminated from cells of a mammalian epithelium and abluminal portions of the tunica propria. Mammalian epithelial tissue used in this aspect of the invention is preferably derived from urinary bladder, intestine, or any other mammalian epithelial tissue. Further embodiments feature a composition shaped to conform to a diseased or defective cardiac valve such as at least a portion of a pulmonic valve, aortic valve, right or left atrioventricular valve, or the myocardium.
In still another embodiment, the invention features a composition comprising epithelial basement membrane, tunica propria, and submucosa. The epithelial basement membrane and tunica propria are delaminated from the cells of an epithelium and from the tunica muscularis of a mammalian epithelial tissue.
In yet another embodiment, the invention features a composition comprising epithelial basement membrane, tunica propria, and smooth muscle cells of the tunica muscularis, all delaminated from epithelial cells of a mammalian epithelium.
The composition, according to the invention, is not limited to merely the embodiments enclosed. Rather, the composition, according to the invention, comprises one or more layers of an epithelial tissue in combination with at least a portion, preferably the entire, intact epithelial basement membrane.
In another aspect, the invention provides methods for inducing restoration or repair of diseased or defective cardiac tissue. A preferred method of the invention comprises the step of contacting a host tissue with a devitalized matrix derived from a mammal. The devitalized matrix comprises at least a portion of an epithelial basement membrane and tunica propria immediately subjacent to the basement membrane. In preferred embodiments, methods of the invention comprise inducing endogenous epithelial repair using tissue regenerative compositions of the invention.